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41.
Summary Pre-implantation-stage embryos from rats, mice, and guinea-pigs were transferred to a non-uterine site — the anterior chamber of the eye — of female recipients. All 9 combinations of transfers were performed: 3 allogeneic (intraspecies) transfers as controls, and 6 xenogeneic (interspecies) transfers. Implantation, as judged by extravasation from blood vessels of the iris or ciliary body occurred with success rates of 90.4% per transfer in the control rat group, 76.9% in the control mouse group, and 81.8% in the control guinea-pig group. Significantly reduced implantation rates occurred in the rat to guinea-pig (0%), mouse to rat (46.9%), mouse to guinea-pig (6.7%), and guinea-pig to rat (0%) groups compared to controls. Reductions, although not significant, also occurred in the other 2 groups: rat to mouse (77.8%), and guinea-pig to mouse (44.4%). These results together with some ultrastructural and lightmicroscopical observations suggest a degree of species specificity involved in the vascular response to the implanting embryo. We propose that the peri-implantation embryo produces a signal(s) which is to some extent species specific and which in the normal allogeneic situation is responsible for the early vascular effects seen at implantation in most eutherian mammals. 相似文献
42.
43.
Kazuhiro Tanaka 《Archives of microbiology》1990,155(1):18-21
The ability of Desulfovibrio vulgaris strain Marburg (DSM 2119) to oxidize alcohols was surveyed in the presence and absence of hydrogen-scavenging anaerobes, Acetobacterium woodii and Methanospirillum hungatei. In the presence of sulfate, D. vulgaris grew not only on ethanol, 1-propanol, and 1-butanol, but also on isobutanol, 1-pentanol, ethyleneglycol, and 1,3-propanediol. Metabolism of these alcohols was simple oxidation to the corresponding acids, except with the last two substrates: ethyleneglycol was oxidized to glycolate plus acetate, 1,3-propanediol to 3-hydroxypropionate plus acetate. Experimental evidence was obtained, suggesting that 2-methoxyethanol was not utilized by all the cells of strain marburg, but by a spontaneous mutant. 2-Methoxyethanol was oxidized to methoxyacetate by the mutant. Co-culture of strain Marburg plus A. woodii grew on ethanol, 1-propanol, 1-butanol, and 1,3-propanediol in the absence of sulfate. Co-culture of strain Marburg plus M. hungatei grew on ethanol, 1-propanol, and 1-butanol, but not on ethyleneglycol and 1,3-propanediol, Co-culture of the mutant plus A. woodii or M. hungatei did not grow on 2-methoxyethanol. 相似文献
44.
The ethanol-oxidizing, proton-reducing Pelobacter acetylenicus was grown in chemostat cocultures with either Acetobacterium woodii, Methanobacterium bryantii, or Desulfovibrio desulfuricans. Stable steady state conditions with tightly coupled growth were reached at various dilution rates between 0.02 and 0.14 h-1. Both ethanol and H2 steady state concentrations increased with growth rate and were lower in cocultures with the sulfate reducer < methanogen < homoacetogen. Due to the higher affinity for H2, D. desulfuricans outcompeted M. bryantii, and this one A. woodii when inoculated in cocultures with P. acetylenicus. Cocultures with A. woodii had lower H2 steady state concentrations when bicarbonate reduction was replaced by the energetically more favourable caffeate reduction. Similarly, cocultures with D. desulfuricans had lower H2 concentrations with nitrate than with sulfate as electron acceptor. The Gibbs free energy (G) available to the H2-producing P. acetylenicus was independent of growth rate and the H2-utilizing partner, whereas the G available to the latter increased with growth rate and the energy yielding potential of the H2 oxidation reaction. The critical Gibbs free energy (Gc), i.e. the minimum energy required for H2 production and H2 oxidation, was-5.5 to-8.0 kJ mol-1 H2 for P. acetylenicus,-5.1 to-6.3 kJ mol-1 H2 for A. woodii,-7.5 to-9.1 kJ mol-1 H2 for M. bryantii, and-10.3 to-12.3 kJ mol-1 H2 for D. desulfuricans. Obviously, the potentially available energy was used more efficiently by homoacetogens > methanogens > sulfate reducers. 相似文献
45.
Jose L. Vega Vicki L. Holmberg Edgar C. Clausen James L. Gaddy 《Archives of microbiology》1988,151(1):65-70
Intrinsic growth and substrate uptake parameters were obtained for Peptostreptococcus productus, strain U-1, using carbon monoxide as the limiting substrate. A modified Monod model with substrate inhibition was used for modeling. In addition, a product yield of 0.25 mol acetate/mol CO and a cell yield of 0.034 g cells/g CO were obtained. While CO was found to be the primary substrate, P. productus is able to produce acetate from CO2 and H2, although this substrate could not sustain growth. Yeast extract was found to also be a growth substrate. A yield of 0.017 g cell/g yeast extract and a product yield of 0.14 g acetate/g yeast extract were obtained. In the presence of acetate, the maximum specific CO uptake rate was increased by 40% compared to the maximum without acetate present. Cell replication was inhibited at acetate concentrations of 30 g/l. Methionine was found to be an essential nutrient for growth and CO uptake by P. productus. A minimum amount of a complex medium such as yeast extract (0.01%) is, however, required. 相似文献
46.
The effect of optic nerve transsection on proteolytic degradation of axonally transported proteins in the superior colliculus of the rabbit was studied. Proteolysis of labeled proteins was determined in vitro in small pieces of the superior colliculus. Within 2 hours after sectioning the optic nerve there was a decreased degradation of slowly transported labeled proteins in the nerve terminals in the superior colliculus.Special Issue dedicated to Prof. Holger Hydén. 相似文献
47.
Abstract IncP group plasmid pRL180 was conjugally transferred from Agrobacterium tumefaciens LBA928 into extra-slow-growing (ESG) Bradyrhizobium japonicum strains and between ESG strains, RJ17W and RJ12S. pRL180 was integrated into the chromosome of RJ12S, RJ17W and RJ19FY. ESG strains efficiently transferred pRL180 into Escherichia coli at about a 3 × 10−5 frequency. IncW group plasmid pTY97 was transferred in intergeneric matings from E. coli into ESG strains at a high frequency of 2.5 × 10−3 ; between RJ17W and RJ12S transfer was about 5.6 × 10−4 . pTY97 was maintained as an R' plasmid in RJ12S. The R' plasmid was resolved upon transfer into E. coli C where only pTY97 was autonomously replicated. 相似文献
48.
Data are presented from a 16-month study of proboscis monkeys in an area of mixed coastal forest in Sarawak. The population
density, social organization, and feeding and ranging behavior are described in detail. Results are compared with those from
other primates in an attempt to understand why females of certain species (including proboscis monkeys) transfer between social
groups. The scarcity of available food and reasons for the limited habitat preferences of proboscis monkeys are also discussed. 相似文献
49.
Roderick A. Capaldi Diego Gonzalez Halphen Yu-Zhong Zhang Wayne Yanamura 《Journal of bioenergetics and biomembranes》1988,20(3):291-311
There is a renewed interest in the structure and functioning of the mitochondrial respiratory chain with the realization that a number of genetic disorders result from defects in mitochondrial electron transfer. These so-called mitochondrial myopathies include diseases of muscle, heart, and brain. The respiratory chain can be fractionated into four large multipeptide complexes, an NADH ubiquinone reductase (complex I), succinate ubiquinone reductase (complex II), ubiquinol oxidoreductase (complex III), and cytochromec oxidase (complex IV). Mitochondrial myopathies involving each of these complexes have been described. This review summarizes compositional and structural data on the respiratory chain proteins and describes the arrangement of these complexes in the mitochondrial inner membrane. This biochemical information is provided as a framework for the diagnosis and molecular characterization of mitochondrial diseases. 相似文献
50.
Mark L. Paddock Scott H. Rongey Edward C. Abresch George Feher Melvin Y. Okamura 《Photosynthesis research》1988,17(1-2):75-96
Many herbicides that inhibit photosynthesis in plants also inhibit photosynthesis in bacteria. We have isolated three mutants of the photosynthetic bacterium Rhodobacter sphaeroides that were selected for increased resistance to the herbicide terbutryne. All three mutants also showed increased resistance to the known electron transfer inhibitor o-phenanthroline. The primary structures of the mutants were determined by recombinant DNA techniques. All mutations were located on the gene coding for the L-subunit resulting in these changes Ile229 Met, Ser223 Pro and Tyr222 Gly. The mutations of Ser223 is analogous to the mutation of Ser264 in the D1 subunit of photosystem II in green plants, strengthening the functional analogy between D1 and the bacterial L-subunit. The changed amino acids of the mutant strains form part of the binding pocket for the secondary quinone, Q
b
. This is consistent with the idea that the herbicides are competitive inhibitors for the Q
b
binding site. The reaction centers of the mutants were characterized with respect to electron transfer rates, inhibition constants of terbutryne and o-phenanthroline, and binding constants of the quinone UQ0 and the inhibitors. By correlating these results with the three-dimensional structure obtained from x-ray analysis by Allen et al. (1987a, 1987b), the likely positions of o-phenanthroline and terbutryne were deduced. These correspond to the positions deduced by Michel et al. (1986a) for Rhodopseudomonas viridis.Abbreviations ATP
adenosine 5-triphosphate
- Bchl
bacteriochlorophyll
- Bphe
bacteriopheophytin
- bp
basepair
- cyt c2+
reduced form of cytochrome c
- DEAE
diethylami-noethyl
- EDTA
ethylenediamine tetraacetic acid
- Fe2+
non-heme iron atom
- LDAO
lauryl dimethylamine oxide
- Pipes
piperazine-N,N-bis-2-ethane-sulfonic acid
- PSII
photosystem II
- RC
reaction center
- SDS
sodium dodecylsulfate
- Tris
tris(hydroxy-methyl)aminomethane
- UQ0
2,3-dimethoxy-5-methyl benzoquinone
- UQ10
ubiquinone 50 相似文献